7．Satellites play big roles in modern life．Some look downward to monitor environmental conditions on Earth．Others look outward in search of major solar flares（耀斑） that can trouble the transmission（传送） of electrical power to homes and businesses．Some spy on our enemies．Others relay communications around the globe．But all of these million-dollar wonders of technology can be knocked out by a collision with space junk---debris （碎片 ）from satellites and other earthly technology orbiting high above the planet．Now，a teen from Jordan has designed a satellite to chase down space junk，collect it and then deal with it．
Even bits of space junk as small as dots of paint pose a threat，says Dana．That's because this debris orbits our planet at speeds up to some 28，200kilometers per hour．Such high speed explains why tiny paint dots have damaged the windshields of space shuttles so badly that they needed to be replaced．
Researchers have come up with many ideas for getting rid of space junk．Some have suggested vaporizing（蒸发） small bits with lasers．Others have proposed launching satellites to collect the debris．Dana's design falls into this category．
Here's how hers would work：A radar system aboard the satellite would scan and find a piece of space junk．Then，thrusters（推进器）would change the satellite's orbit so that it could chase down the errant object．As the satellite closed in on its prey，cameras would keep it on target．
At the last minute，a door that leads to a container would open．This container needs to be strong so that it doesn't break apart when the satellite swallows the space junk，Dana explains．Finally，when the trash container was full，it would be lowered toward the earth on a kilometer-long cable and its contents released into the upper atmosphere．There，the space junk would harmlessly burn up just like a meteor （流星） does．Meanwhile，her satellite would roll the container back up so that it could collect more trash．
24．What is focused on in the first paragraph？D
A．The types of satellites being categorized into．
B．The tracks of satellites orbiting above the planet．
C．The sources of space junk coming from．
D．The danger that satellites face in space．
25．Why can small pieces of space junk threaten satellites？A
A．They travel at a very high speed．
B．They are difficult to track by satellites．
C．They can blow up into millions of pieces．
D．They are as soft as a ball in the air．
26．The underlined words"the errant object"refer toB．
A．the radar system that scans space junk
B．the space junk that travels in disorder
C．the satellite that doesn't keep its track
D．the camera that can't keep space junk on target
27．According to the Dana's design，space junk in her satelliteC．
A．will be swallowed and stored in its trash bin
B．will be broken apart in the trash container
C．will be destroyed by heat in the upper atmosphere
D．will be transported to the earth through a cable．
分析 本文属于说明文阅读，作者通过这篇文章主要向我们描述了美国一个15岁的学生发明了一种可以收集太空垃圾的设备并说明了工作原理．
解答 24．D．判断推理题．文章中第一段提出了But all of these million-dollar wonders of technology can be knocked out by a collision with space junk---debris （碎片 ）from satellites and other earthly technology orbiting high above the planet．这些都是表示的太空垃圾的危险之处，即卫星所面临的危险，所以答案是D．
25．A．细节理解题．根据文章第二段第二三句That's because this debris orbits our planet at speeds upto some 28，200 kilometers per hour．Such high speed explains why tiny paint dots have damaged the windshields of space shuttles so badly that they needed to be replaced．提到这些太空碎片速度快是它们威胁卫星的原因，所以答案是A．
26．B．判断推理题．由文章第四段划线短语前面的句子A radar system aboard the satellite would scan andfind a piece of space junk可知其意是那些四处逃窜的太空垃圾，所以答案是B．
27．C．细节理解题．根据文章There，the space junk would harmlessly burn up just like a meteor （流星） does可知他的发明是利用燃烧的方法消除垃圾，所以答案是C．
点评 考察学生的细节理解和推理判断能力，做细节理解题时一定要找到文章中的原句，和题干进行比较，再做出正确的选择．在做推理判断题不要以个人的主观想象代替文章的事实，要根据文章事实进行合乎逻辑的推理判断．
